1. Field of the Invention
This invention relates to a composite parts, as well as a method for the manufacture of such a composite part.
2. Brief Description of the Prior Art
Constructions that utilize the sandwich principle are characterized by high flexural strength and simultaneously by low weight. For this reason, the use of these components has become very common in the transportation industry, and in particular in the railroad industry. For structures that are subjected to high loads, it is logical to manufacture these sandwich composites from metal materials.
To connect additional components to the sandwich components, or to connect different sandwich components to one another at any desired angles, profiles are integrated for the discharge of forces and for the attachment of connecting points. Larger sandwich components are constructed by connecting a plurality of smaller sandwich components, which are called basic components below, into a large sandwich component, as a function of the requirements of the specific application.
EP 0 544 498 discloses composite parts made of sandwich components and profiles for the discharge of forces, in which the profiles are welded to a web that stands perpendicular to the cover layer of the sandwich component between two basic components that are butt-welded to each other on their ends. This system uses a reinforcement for the attachment of the profiles, which reinforcement results from the fact that both the sandwich components and the basic components are normally closed and are reinforced in their terminal area by U-shaped reinforcement profiles with the open area pointing outward and inserted in place of the core. With this type of attachment, the weld seam is along the contact points between the cover surface and the profile.
In a composite part disclosed in EP 0 644 096, the profiles are welded to a connecting surface either on the edge on the connecting area between two basic components that are reinforced with U-shaped reinforcement profiles, or are riveted to the cover layer which is underlaid with hollow reinforcement profiles.
In all the composite parts of the prior art, the profile is welded or riveted to the sandwich component, as a result of which there is a spot or linear discharge of forces from the profile into the sandwich component. However, such a construction requires that the sandwich component be reinforced in the vicinity of the weld. The reinforcement is created by extra hollow reinforcement profiles instead of the metal core, or by U-shaped reinforcement profiles in the vicinity of the butt weld between two basic components.
One disadvantage of such composite parts is the difficulty of constructing large components with a plurality of profiles for the discharge of forces. Large components, such as the side walls of a railroad car, for example, must either be constructed from many small composite parts, so that the profiles for the discharge of forces can be placed at the butt joints, or the sandwich components must be provided in advance at the appropriate locations with hollow reinforcement profiles instead of the core. In all cases, it is no longer possible to subsequently attach profiles for the discharge of forces, unless a reinforcement profile has been provided at the appropriate points. It is also expensive and time-consuming to construct larger components from many small composite parts. Joint corrosion or contact corrosion problems also occur at the weld seams or rivet connections and have a significant effect on the useful life of the components.
The object of this invention is to create a composite part that consists, of a sandwich component and one or more profiles for the discharge or forces, with which it is possible to construct larger components, on which a plurality of force discharge points are required, from a few large composite parts. It must also be possible, on the composite parts, to subsequently attach profiles at any desired points without adversely affecting the discharge of forces.
The composite part as claimed by the invention makes it possible to easily manufacture components that have a plurality of profiles for the discharge of forces, by optimally adapting the dimensions of the composite part, plus the profiles, to the dimensions of the component to be formed, without having to interrupt and reconnect the sandwich components at the force discharge points, which significantly simplifies the process of constructing the components and results in cost reductions. The profiles for the discharge of forces are connected to the sandwich component after the sandwich component has been optimally adapted, in terms of its dimensions, to the component to be formed. Because the locations of the connections of the profile for the discharge of forces are independent of the location of the butt joints or the reinforcement points of the sandwich components, additional profiles can be connected to the existing composite part at any later time as necessary, which increases the variability of the composite parts. The quality of the connection between the profile and the sandwich component is also improved by the flat connection of the profiles, as a result of which the construction of the composite parts is stabilized. It also becomes possible to increase the useful life by preventing corrosion in the gaps at the connections or contact corrosion at the joints.
For the flat connection of the profiles to the sandwich components, the sandwich components have at least one connecting surface adjacent to the cover layer. The overall geometry of the profiles used is adapted to the specific application. Depending on whether additional parts are welded, bolted or riveted on, the profiles have additional areas or T elements or slotted cavities for the attachment of a bolt head or rivet head. This shaping can be advantageously achieved by using extruded profiles as the force-discharge elements.
The flat connection, which has advantages over the welding of the profiles to the reinforced sandwich components, can then be accomplished by gluing the profile to the sandwich component, although the metal profile is preferably soldered to the metal cover layer. As a result, an improved adhesive bond is achieved, in particular if the structure is likely to be exposed to severe vibrations.
The following part of the description relates to a method for the manufacture of the composite part claimed by the invention.
A method disclosed in EP 0 405 889 describes the manufacture of composite parts in which, in a first step, the sandwich components are fabricated with reinforcements in the positions provided for the profiles or with butt joints between basic components that are reinforced in the peripheral area, and in a second step the profiles are welded to the reinforced areas with at least one seam.
The first step in the method of EP 0 405 889, in addition to the actual manufacture of the sandwich components, includes additional operations, because the reinforcements must be attached to the positions provided for the profiles, which interrupts the insertion of the metal core and makes the manufacture of sandwich components reinforced in this manner very complex, time-consuming and expensive. Moreover, the reinforcement profiles cannot be installed at any desired angle with respect to the honeycomb structure, which represents a limiting of the potential applications. The manufacture of sandwich components that are made of basic components butted up against each other also increases the cost and time required for the completion of the first step. If a plurality of weld seams are used to fasten the profile to the reinforced sandwich component, the number of operations in the second step must also be increased accordingly.
The object of the present invention is also a method for the manufacture of a composite part as claimed by the invention that consists of the sandwich component and the profile for the discharge of forces, in which the number of steps in the method and the number of operations included in these individual steps are minimized.
The present invention teaches that the profile or profiles are connected to the sandwich part during the process of manufacturing the sandwich component.
In this method as claimed by the invention, it is advantageous that the simultaneous manufacture of the sandwich components and the connection of the profiles eliminates the entire second step in the operation. Because the profiles can be connected to the honeycomb structure of the core even in areas where there are no reinforcement profiles and without considering a specific orientation with respect to the honeycomb structure of the core, it is also possible to use the method claimed by the invention to fabricate composite parts with profiles that are oriented in any desired position.
During the manufacture of the sandwich component, the parameters of this process are utilized to connect the profile to the sandwich component. Because the cover layers and the honeycomb core are metal components, it is advantageous to connect the cover layers to the core by soldering. It is particularly advantageous if solder-plated cover layers are used to solder the cover layers to the core. Once the solder-plated side has come in contact with the metal core, the soldering process proceeds when the components have been heated to a temperature that is above the melting point of the solder in the absence of air, in particular in a vacuum. The solder becomes liquefied and accumulates at the points of contact between the cover layer and the webs of the honeycomb-shaped structure of the core, so that a soldered sandwich component is formed as the structure cools.
The parameters of the manufacturing process of the sandwich componentxe2x80x94such as the temperature that occursxe2x80x94can be utilized to simultaneously connect the profile to the sandwich component. For this purpose, the profile is also preferably soldered to the sandwich component. In the method claimed by the invention, cover layers are preferably used which are solder-plated on the side facing the profile, so that as a result of the temperature that is achieved during the manufacturing process, the solder on this side of the cover layer is also liquefied, and in the absence of air accumulates at the points of contact between the profile and the cover layer. As a result, when the composite part cools, there is a flat connection between the profile and the sandwich component. The following description indicates additional details, features and advantages of the invention.